In a nuclear reactor of an indirect cycle which generates electric power by rotating a turbine with steam which is not contaminated by radiation, a steam generator or a heat exchanger is provided between the primary coolant system and the secondary coolant system.
For example, in a loop-type fast breeder, heat of a primary sodium system (primary coolant system) heated by cooling a reactor core is transmitted to a secondary sodium system (secondary coolant system) by an intermediate heat exchanger, and heat of the secondary sodium system is transmitted to a water/steam system by an evaporator and a superheater. Further, in a pool-type fast breeder reactor in which a reactor vessel is increased in size and a pump of a primary sodium system and an intermediate heat exchanger are integrated in the reactor vessel, likewise, heat of the primary sodium system is transmitted to the secondary sodium system by the intermediate heat exchanger, and heat of the secondary sodium system is transmitted to a water/steam system by a steam generator.
Furthermore, in a nuclear reactor other than the fast breeder, e.g., a pressurized light water reactor, heat of a primary cooling water heated by cooling a reactor core is transmitted to a water/steam system by a steam generator.
In the above-described nuclear reactor of the indirect cycle, however, since transmission of heat between the respective cooling systems is carried out by the steam generator or the heat exchanger which is independent or integrated in each chamber and connected through a pipe, the entire cooling system becomes complicated and large. In particular, in the fast breeder or the like aiming at power generation, the primary coolant system is constituted by many loops, and a plurality of loops of the secondary coolant system are connected to each of the loops of the primary coolant system. Therefore, the number of pipes, pumps, heat exchangers or steam generators and others is increased, and complication or an increase in size of the cooling system is prominent. Therefore, a manufacturing cost of a nuclear steam supply system (HSSS: including the nuclear reactor, the secondary and subsequent cooling systems, the heat exchanger and the steam generator) reaches a huge value, and its maintenance management requires many work forces and monitoring facilities, and hence a large amount of cost is needed.
It is to be noted that the pipes or the like of the cooling systems are reduced in the pool-type fast breeder reactor as compared with the loop-type fast breeder, thereby achieving simplification or a reduction in size of the cooling systems as compared with the loop-type fast breeder. However, the intermediate heat exchanger or the steam generator is still required, it cannot be said that simplification or a reduction in size of the cooling systems is sufficient, and further simplification or a reduction in size of the cooling systems is demanded.